This invention relates to an apparatus for withdrawing a fiber web discharged by a web delivering assembly of a carding machine and for gathering the web to form a sliver. The apparatus includes a sliver trumpet equipped with calender rolls and arranged downstream of the web delivering assembly, as viewed in the direction of web discharge.
Generally, the web delivering assembly, such as the crush rolls of a carding machine, discharge an extremely thin fiber web which is composed of interlocked individual fibers and which has a width of approximately 1,000 mm. The fiber web is thus exposed along a great width to the effect of air currents and further, the web has to be gathered into a rope-like sliver from such a large width dimension. The weight of the web is only about 5 g/m.sup.2, so that within the fiber web there are only very weak cohesion forces and therefore the running speed has to be significantly limited. Close the crush rolls, there is arranged a sliver trumpet which gathers the web into a sliver. Between the crush rolls and the trumpet the web is of triangular configuration. This method has the disadvantage that the running speed of the fiber web, as it emerges from the crush rolls, has to remain--in the absence of appropriate measures--relatively small to avoid fiber web rupture. In U.S. Pat. No. 4,213,553 (Ferdinand Leifeld) issued July 22, 1980, an arrangement is disclosed wherein the sliver trumpet may be brought in the immediate vicinity of the web delivering assembly for normal operation of a card. As a result, the web passes directly from the web delivering assembly to the sliver, thus largely eliminating adverse effects of air currents. The calender unit which comprises the sliver trumpet and the calender rolls is movable towards and away from the crush rolls to assume an operative position in the immediate vicinity of the crush rolls in the normal run and an inoperative, withdrawn position for start-up, maintenance or cleaning.
For facilitating start-up operation which involves the passing of the leading end of the web through the various roll components, it is known to use a start-up tray which is situated underneath the crush rolls (and a stripper roll preceding the crush rolls) for guiding the leading end of the web in between the crush rolls. After start-up, for the normal operational run, the calender assembly is brought into its normal operational position close to the crush rolls and the delivery speed is increased. During normal operation, however, the presence of the start-up tray is not desired, because debris dropping out of the web in the zone of the stripping roll and the crush rolls may accumulate on the start-up tray and may therefore interfere with the operation of the card.